Canon RF 24-240mm f/4-6.3 IS USM - My Favorite Digital Lens
Is better necessarily better? Over the last couple of years, camera manufacturers have been obsessing over the development of better with regards to quality in image reproduction. In doing so, material concerns such as improving corner to corner sharpness, definition of details at higher resolution, and correction of optical aberration across the aperture range have become gospel - even when shot at maximum aperture. Because of that, our ability to capture reality as close to real life has never been more accurate.
In addition to that, camera manufacturers have also focused greater attention in making faster lenses. These days, it seems that every camera and third party lens manufacturer have made an ultra fast lens. Leica has its benchmark Noctilux with a maximum aperture of f/0.95. So does Nikon, with its benchmark S Noct also with a maximum aperture of f/0.95. Canon has a mid-range zoom lens with an industry first maximum aperture of f/2 in addition to having a pair of newly released prime lenses with a maximum aperture of f/1.2.
However, all this betterness comes at a not-so-hidden cost. In order to achieve optical designs that are both superior in image quality across the aperture range and large in maximum aperture, the size of most modern lenses have swollen to a point beyond what is practical in normal use. Simply put, they’re just too ridiculously large and heavy for me to carry around. Thus, it comes as no surprise that I have found joy in the least likely of lenses - the Canon RF 24-240mm f/4-6.3 IS USM - a much slower lens with inferior image quality.
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 135mm and ISO 1600
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM@ 90mm and ISO 1600
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM@ 240mm and ISO 1600
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM@ 50mm and ISO 1600
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 50mm and ISO 1600
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 75mm and ISO 800
Strictly speaking, the RF 24-240 is not a 24mm lens at its widest angle of view. Between 24-28mm, the RF 24-240 exhibits a horrible case of vignetting, even when stopped down. On top of that, the RF 24-240 can only open up to f/4 from 24-27mm. From 28-40mm, the maximum aperture is f/4.5. As such, the RF 24-240 should really be called the RF 28-240mm f/4.5-5.6. However, the powers-to-be at Canon thought the extra angle of view and increased maximum aperture would make the RF 24-240 more marketable to its customer base.
In addition to this sleight-of-hand naming convention, the RF 24-240 also suffers from a horrible case of barrel distortion. Most notably, barrel distortion shows up in the background at wider angles of view, even when horizontal and vertical lines are at a considerable distance. Moreover, the RF 24-240 also exhibits noticeable pincushion distortion in the foreground, when shooting close up at tighter angles of view. But to be fair, barrel distortion at the wide end and pincushioning at the tight end are expected for super zoom lenses.
Mind you, all this isn’t strictly true. At the time of writing, I discovered the problem of vignetting and distortion can be fixed with Canon’s proprietary imaging software - Digital Photo Professional 4. But, as of this moment, I have all-of-a-sudden discovered that the Profiles for Lens Correction in Adobe Lightroom is working. In fact, it fixes the issue of vignetting and distortion much better than Canon’s own imaging software. Lightroom retains more of the original image, while Canon appears to crop a large portion of the image automatically.
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 24mm (cropped) and ISO 800. Note: Without Fill Flash, getting the optimal exposure to retain details in background highlights and subject shadows is not possible. As such, subject was underexposed to prevent the background highlights from becoming completely blown.
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 50mm and ISO 800. As an addendum to the previous image. A better solution was to turn around, where the subject was more optimally exposed to a background that was slightly more in shadow.
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 50mm and ISO 800
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 75mm and ISO 800
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 50mm and ISO 800
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 24mm (cropped) and ISO 800
Still, the RF 24-240 is not optically designed for professional application. It is a relatively light weight lens encased in a compact plastic shell. For that reason, many enthusiasts seeking the best lens for optimal image reproduction will pass over the RF 24-240 - which really is crying a shame. The fact the RF 24-240 is not made for professional application is precisely why it is my go-to lens for digital imaging. Though it might not take the most technically precise photos, it has the right mix of size and focal range to get me the perfect shot.
Of course, there are those who will point out that the RF 24-240 is a slow lens. I mean, how convenient can the RF 24-240 be if its maximum aperture at its widest angle of view is f/4? Granted at wider angles of view, the threshold in satisfying the reciprocal rule is much less demanding at lower shutter speeds. But at 240mm, one must shoot at 1/250s in order to avoid camera shake - which can be a challenge under low light conditions. At 240mm compared to its widest angle of view, you are essentially losing three stops.
Thankfully in the era of digital imaging, we have the convenience of high ISO imaging to compensate for the inherent limitations of much slower lenses. Because of that, the RF 24-240 is still very usable in suboptimal or low light conditions - even when shooting at 240mm. In addition to that, the RF 24-240 also has in-lens image stabilization up to five stops. That means the RF 24-240 can shoot at much lower shutter speeds in lower light without image blur - assuming the subject in-frame is cooperating by remaining motionless for the shot.
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 50mm and ISO 6400. Image required considerable color correction, given the horrible interior lighting.
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 240mm and ISO 6400. This image required even more color editing than the previous image, including the use of local color and exposure corrections. Additionally, I also dodged the white of the eyes and teeth. That might have been going a little overboard.
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 50mm and ISO 800
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 24mm (cropped) and ISO 6400
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 24mm (cropped) and ISO 6400
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 50mm and ISO 6400
That said, why would anyone want to shoot the RF 24-240 at 240mm in low light? Generally, the need to shoot at tighter focal lengths for reach with such a lens only makes sense when there is enough available light. That is to say, the RF 24-240 is not made for low light capture at tighter focal lengths. Usually in low light, the RF 24-240 is made to shoot at wider focal lengths, when it can be set at much lower shutter speeds and benefit from a greater margin of error in focusing from increased depth of field - even at maximum aperture.
Yes, the RF 24-240 is not made for documenting your child’s piano recital or school performance (in subdued light and from a long distance). Moreover, the RF 24-240 is not made for indoor action photography shot from the stands, where freezing motion in poor light is required. For both shooting situations, you need a dedicated telephoto lens with a larger maximum aperture. Rather, what the RF 24-240 is intended for is recreational use. It is a lightweight lens with immense reach that is simply a joy to use in normal everyday light
That means the RF 24-240 is the perfect outdoor lens to carry around - especially on vacation or a hike. For my sake on this blog, I found the RF 24-240 extremely versatile in addressing different photo opportunities on the streets of Hong Kong. Having a broad focal range from 24mm to 240mm plus a minimum focusing distance of 1.13ft (or 0.34m) at 24mm and 2.56ft (or 0.78m) at 240mm is a luxury. This is true for a rangefinder photographer like me who is normally limited to one focal length and a minimum focusing distance of 2.3ft (or 0.7m).
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 24mm (cropped) and ISO 800
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 75mm and ISO 800
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 75mm and ISO 800
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 24mm and ISO 800. Notice the vignetting
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 24mm and ISO 800. Notice the vignetting
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 135mm and ISO 800
In terms user experience, shooting with the RF 24-240 feels intuitive. It snaps to focus quickly. The rubberized surface on the zoom ring is ample in coverage and feels appropriate to the touch. Moreover, the throw of the zoom ring has the right amount of tension. It is neither too loose or too tight. In contrast, the textured focusing ring of the RF 24-240 feels distinct from the zoom ring. It is narrower and has a slightly looser throw than the zoom ring. Overall, the RF 24-240 feels good in hand and perfectly balanced on the Canon EOS R.
As for image quality, the RF 24-240 isn’t too bad - that is - after you resolve the vignetting, distortion, and odd chromatic aberration with the correct profile for lens correction on Adobe Lightroom or use Canon’s Digital Photo Professional 4. Still, the image quality rendered by the RF 24-240 isn’t exactly praiseworthy. It renders noticeably less sharp at the edges and corners. Still, the RF 24-240 is sharp where sharpness counts. And in the end, isn’t that the already good enough? For my sake, I certainly find the image quality good enough.
However, if good enough is not good enough, and you insist on better, then the RF 24-240 is not the lens for you. It is just too full of imperfections and requires proprietary imaging software to fix its many flaws in image reproduction. That said, what is better is generally larger and heavier, requiring a greater commitment to use - typical of a super zoom or telephoto lens. As such, what is better is seldom ever used. Most of us just end up relying on our best prime lens in opting for better image quality as oppose to getting the perfect shot.
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 75mm and ISO 800
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 105mm and ISO 800
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 240mm and ISO 800
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 35mm and ISO 800
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 240mm and ISO 800
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 240mm and ISO 800
In the end, I suppose that is the point of the exercise from this blog entry. In our obsession over better image quality, we tend to forget about the importance of getting the perfect shot. Superzoom lenses like the RF 24-240 offers the reach in focal length to frame photo opportunities with greater compositional precision. Thing is, if you ask anyone to pick between better optical image quality or getting the perfect composition, I believe most would likely pick the latter. Personally, I know I would.
So to answer the question at the beginning of this blog entry, better isn’t better, since superior optics will not guarantee one the perfect shot. Besides, better is just too heavy to be taken out to take that perfect shot.
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 24mm and ISO 1600. UPDATED: October 14, 2019. It seems that all-of-a-sudden, the Profiles for the Len Correction in Adobe Lightroom is working. I don’t know if it’s because I’ve updated Canon Digital Photo Professional 4 or because there has been an update to Lightroom that I’m not aware of downloading. In any event, this is currently the best remedy to the vignetting and distortion issue.
Canon EOS R + Canon RF 24-240mm f/4-6.3 IS USM @ 24mm and ISO 1600. UPDATED: October 17, 2019. If you compare this, the original RAW image to the above corrected image, you will notice that the vignetting was essentially corrected by fixing the distortion - that is to say - pulling the corners away from the center just a little more. As you can see, the angle of view, given the distortion, is actually wider here in the original image, than the corrected image above.
All images have been tweaked on Adobe Lightroom. The optical aberration of the final image has been fixed in the latest version of Canon’s Digital Photo Professional 4. The process is automatic.
UPDATED: It seems that all-of-a-sudden, the Profiles for the Len Correction in Adobe Lightroom is working. I don’t know if it’s because I’ve updated Canon Digital Photo Professional 4 or because there has been an update to Lightroom that I’m not aware of downloading. In any event, this is currently the best remedy to the vignetting and distortion issue. October 14, 2019
Please note the official minimum focusing distance at 24mm is 1.64ft (or 0.5m), which differs significantly from what I measured on my own. I cannot account for the discrepancy. The official minimum focusing distance at 240mm is more or less consistent to my own measurement.
